Force measuring device

Abstract

A force measuring device includes a rigid base plate and a first diaphragm symmetrical about a central normal axis and arranged in spaced parallel relationship to the base plate. An elastic connection between the base plate and a peripheral rim of said first diaphragm hermetically closes a cavity formed between the base plate and first diaphragm. A first projection is formed, for force introduction to the device, on an outer surface of the first diaphragm and extends along the central normal axis; a second projection extends from an inner surface along the central normal axis toward the base plate. A displacement sensor is arranged in the cavity between the base plate and second projection for sensing any displacement therebetween upon force application to the device, to generate an electrical signal indicative of the force applied.

I claim: 
     
       1. A force measuring device comprising: a substantially rigid base plate;   a first diaphragm symmetrical about a central normal axis and being arranged in spaced, substantially parallel relationship to said base plate;   an elastic connection between said base plate and a peripheral rim of said first diaphragm, said elastic connection hermetically closing a cavity formed between said base plate and said first diaphragm;   a first projection formed for force introduction to said device on an outer surface of said first diaphragm and extending along said central normal axis;   a second projection extending from an inner surface of said diaphragm along said central normal axis toward said base plate; and   a displacement sensor means arranged in said cavity between said base plate and said second projection for sensing any displacement therebetween upon force application onto said device, and generating an electrical signal indicative of the force applied,   wherein said first diaphragm comprises an outer torsion ring and an inner elastic disk elastically connected to said torsion ring along an inner upper circular line, said torsion ring being elastically connected to said base plate through said rim along a lower outer circular line.   
     
     
       2. The device of claim 1, wherein said displacement sensor means comprises a magnet and a Hall generator means arranged in cooperative proximity for movement relative to each other upon force application onto said device. 
     
     
       3. The force measuring device of claim 1, wherein said inner upper surface circular line and said lower outer circular line are grooves. 
     
     
       4. The device of claim 1, wherein said torsion ring has an essentially quadrangular cross-section and said inner upper and said lower outer circular lines constitute opposite edges of said torsion ring. 
     
     
       5. The device of claim 1, further comprising a second diaphragm arranged on top of said first diaphragm, elastically connected circumferentially with said first diaphragm, rigidly connected at a central position to said first diaphragm and provided with opposite bending elastically in respect to said first diaphragm. 
     
     
       6. The device of claim 1, wherein a plurality of displacement sensor means is provided. 
     
     
       7. The device of claim 6, wherein said plurality of displacement sensor means are arranged in spaced relationship in respect of said central normal axis. 
     
     
       8. The device of claim 6, wherein said plurality of said displacement sensor means are arranged at angular distances around said central normal axis. 
     
     
       9. The device of claim 1, wherein the torsional elasticity of said torsion ring and the bending elasticity of said elastic disk are selected such that non-linearities of the device are compensated. 
     
     
       10. The device of claim 1, wherein the torsional elasticity of said torsion ring and the bending elasticity of said disk are selected such that temperature influences are compensated. 
     
     
       11. The device of claim 1, wherein said displacement sensor means is attached to a peripheral surface of said second projection. 
     
     
       12. The device of claim 1, wherein said second projection has a lower end surface opposing an upper surface of said base plate at a small distance and forming an abutment to prevent overloading of said device. 
     
     
       13. The device of claim 1, wherein said elastic connection is a welded connection. 
     
     
       14. A force measuring device comprising: a first diaphragm having a symmetrical form about a central normal axis;   a second diaphragm of a shape similar to that of said first diaphragm, arranged opposite thereto in substantially parallel spaced relationship and hermetically connected along a circumferential rim thereof for forming a closed cavity between said first and second diaphragms; and   a displacement sensor means arranged within said cavity between said first and second diaphragms for detecting the extent of relative movement between said first and second diaphragms upon force application thereonto,   wherein said first and second diaphragms comprise an outer torsion ring and an inner elastic disk elastically connected to said torsion ring along an inner upper circular line, said torsion rings of said first and second diaphragms being elastically connected to each other along a lower outer circular line.   
     
     
       15. The device of claim 14, wherein each of said first and second diaphragms comprise: a first projection formed for force introduction onto said device on an outer surface of said first and second diaphragms and extending along said central normal axis; and a second projection extending from an inner surface of said first and second diaphragms along said central normal axis, said second projections of said first and second diaphragms having end surfaces opposing each other at a small distance.   
     
     
       16. The device of claim 14, wherein said displacement sensor means comprises a magnet and a hall generator means arranged in cooperative proximity for movement relative to each other upon force application onto said device. 
     
     
       17. The device of claim 14, wherein said torsion ring has an essentially quadrangular cross-section said inner upper and said lower outer circular lines constituting opposite edges of said torsion ring. 
     
     
       18. The device of claim 14, further comprising a third and a fourth diaphragm arranged on top of said first and second diaphragms, respectively, elastically connected circumferentially thereto, rigidly connected to a central position thereto, and provided with opposite bending elasticity in respect thereto. 
     
     
       19. The device of claim 14, wherein a pluarlity of displacement sensor means is arranged at angular distances around said central normal axis. 
     
     
       20. The device of claim 14, wherein there is provided a plurality of displacement sensor means arranged at angular distances around said central normal axis. 
     
     
       21. The device of claim 14, wherein the torsional elasticity of said torsion ring and the bending elasticity of said elastic disk are selected such that non-linearities of the device are compensated. 
     
     
       22. The device of claim 14, wherein the torsional elasticity of said torsion ring and the bending elasticity of said disk are selected such that temperature influences are compensated. 
     
     
       23. In a force measuring device including a first diaphragm, the improvement comprising said diaphragm including: an outer torsion ring;   an inner elastic disk elastically connected to said torsion ring along an inner upper circular line, and provided at an upper surface with a central projection for force introduction;   transducer means connected to a lower surface of said elastic disk; and   wherein said outer torsion ring is adapted to be elastically connected to a support element along a lower outer circular line.   
     
     
       24. The diaphragm of claim 23, wherein said torsion ring has an essentially quadrangular cross-section said inner upper and said lower outer circular lines constituting opposite edges of said torsion ring. 
     
     
       25. The diaphragm of claim 23, wherein the torsional elasticity of said torsion ring and the bending elasticity of said elastic disk are selected such that non-linearities of the device are compensated. 
     
     
       26. The diaphragm of claim 23, wherein the torsional elasticity of said torsion ring and the bending elasticity of said disk are selected such that temperature influences are compensated. 
     
     
       27. The diaphragm of claim 23 further comprising a second diaphragm arranged on top of said first diaphragm, elastically connected circumferentially with said first diaphragm, rigidly connected at a central position to said first diaphragm, and provided with opposite bending elasticity with respect to said first diaphragm. 
     
     
       28. A force measuring device, comprising a first diaphragm including an outer torsion ring and an inner elastic disk elastically connected to said torsion ring by means defining a flexible connection between said ring and disk; mountng means attached to said diaphragm through said torsion ring by second flexible connection means and extending generally parallel to said diaphragm, for defining a hermetically closed cavity between said diaphragm and mounting means;   a first projection formed on an outer surface of the diaphragm disk to transmit a force exerted against the first projection to said device;   a second projection extending from an inner surface of said diaphragm disk towards said mounting means; and   displacement sensor means arranged in said cavity between said mounting means and said second projection for sensing displacement therebetween induced by application of said force against said first projection, said displacement sensor means generating an electrical signal indicative of said force applied to the first projection.